How many rear fog lights does a car have?
3 Answers
One or two. Here is the relevant information: 1. National standards stipulate that the number of rear fog lights can be one or two. Some car owners have noticed that one side of the rear fog light is not lit, which is actually not a malfunction but rather that it was never installed in the first place. If the manufacturer only equips one fog light, according to regulations, it must be installed on the left side of the driving direction. Therefore, if only one rear fog light is lit, it must be the left one. 2. "GB4785 Installation Regulations for External Lighting and Light-signaling Devices of Motor Vehicles and Trailers": For fog lights, the mandatory installation is one, with an optional additional one. The light color must be red. If only one is installed, it must be located on the left side. Generally, fog lights are red or yellow because these two colors have longer wavelengths and stronger penetration. Front fog lights are usually yellow for better penetration, while rear fog lights are generally red, serving both as a warning to vehicles behind. Front fog lights are not mandatory, but rear fog lights must be standard equipment!
I've had many discussions with friends about rear fog lights. As a car enthusiast, I've noticed that most regular sedans only have one rear fog light, typically installed in the lower center of the rear bumper, usually with a red bulb or LED. This design complies with regulations, such as national standards requiring just one sufficiently bright light to avoid excessive costs. Why not install more? Because a single light's beam is adequate to penetrate dense fog, allowing following vehicles to clearly see your outline. Adding more could potentially dazzle other drivers, especially in urban areas where unnecessary use may result in fines. I once encountered heavy fog on the highway and felt a heightened sense of security after turning on the rear fog light. Fog lights should only be activated when visibility drops below 50 meters, and remember to turn them off otherwise. Replacing the bulb is straightforward—you can do it yourself or have it done at an auto repair shop for just a few dozen yuan. The key is to develop the habit of checking the fog light status while driving, ensuring it's not left unused and wasted.
From a technical perspective, rear fog lights are generally designed as a single unit to balance efficiency and safety. I've studied various vehicle models, and it's common for sedans and SUVs to have one rear fog light installed low in the center of the rear. This location is chosen to direct the light onto the ground or fog layer, avoiding reflection into the air that could impair visibility. Why design it as one? Because regulations like the ECE standards emphasize that one light is sufficient, eliminating unnecessary redundancy. However, a few high-end or modified vehicles might feature two, but this isn't the mainstream. The bulb types are mostly LED or halogen, with a typical power rating around 21 watts, capable of improving visibility by over 20% when activated. Fog lights should only be used in extreme weather conditions while driving; avoid blinding others by keeping them on in clear weather. Regularly checking if the bulb is fused is crucial, as simple maintenance can prevent hazards. Safety comes first—following the rules is about preserving lives.
